Peppermint production agriculture, forestry & fisheries ESSENTIAL OIL CROPS

ESSENTIAL OIL CROPS
Production guidelines for peppermint
Peppermint production
agriculture,
forestry & fisheries
Department:
Agriculture, Forestry and Fisheries
REPUBLIC OF SOUTH AFRICA
Peppermint production
February 2012
Department of Agriculture, FORESTRY AND FISHERIES
Directorate: Plant Production
2012 Second print
2009First print
Compiled by Directorate Plant Production in collaboration with
members of SAEOPA and KARWIL Consultancy
Obtainable from
Resource Centre
Directorate Communication Services
Private Bag X144, Pretoria, 0001 South Africa
The web: www.daff.gov.za/publications
Published by
Directorate Communication Services
Department of Agriculture, Forestry and Fisheries
Private Bag X144, Pretoria, 0001 South Africa
Further information or contacts
Directorate Plant Production, Division Industrial Crops
Tel: 012 319 6079/6072
Fax:
012 319 6372
E-mail:
dpp@daff.gov.za
Contents
Part I: General aspects............................................................................. 1
1. Classification .................................................................................. 1
2. Origin and distribution..................................................................... 2
3. Production levels............................................................................. 2
4. Major production areas in South Africa........................................... 3
5. Description of the plant.................................................................... 3
6. Species and cultivars ..................................................................... 5
7. Climatic requirements...................................................................... 5
8. Soil requirements............................................................................ 5
Part II: Cultivation practices..................................................................... 6
1. Propagation..................................................................................... 6
2. Soil preparation............................................................................... 6
3. Planting........................................................................................... 7
4. Fertilisation...................................................................................... 7
5. Irrigation.......................................................................................... 8
6. Weed control................................................................................... 8
7. Pest control..................................................................................... 9
8. Disease control................................................................................ 10
9.Other cultivation practices............................................................... 11
10.Harvesting....................................................................................... 11
iii
Part III: Post-harvest handling...................................................................... 12
1. Sorting and distillation..................................................................... 12
2.Grading............................................................................................ 12
3.Packaging........................................................................................ 12
4.Storage............................................................................................ 12
5.Marketing......................................................................................... 13
Part IV: Production schedules................................................................... 13
Part V: Utilisation....................................................................................... 15
1.Industrial.......................................................................................... 15
2.Cosmetic......................................................................................... 15
3.Medicinal and therapeutic............................................................... 15
4.Other............................................................................................... 15
5. Safety data...................................................................................... 16
References..................................................................................................... 16
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Part I: General aspects
1. Classification
Scientific name: Mentha x piperita
Common names: Peppermint, black mint
Family: Lamiaceae
Of the members of the mint family under cultivation the most important are the
several varieties of peppermint (Mentha x piperita), extensively cultivated for years
as the source of the well-known volatile peppermint oil, used as a flavouring and
therapeutic agent.
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2. Origin and distribution
The origin of peppermint species cannot be determined. Dried leaves were found
in the Egyptian pyramids dating back to 1 000 BC. Two species of mint were
used by the ancient Greek physicians, however, some writers doubt whether
one is the modern peppermint, though there is evidence that M. x piperita was
cultivated by the Egyptians. It is mentioned in the Icelandic pharmacopoeias of
the thirteenth century, but only came into general use in the medicine of Western
Europe about the middle of the eighteenth century, and then was first used in
England.
Pliny the Elder, 79 AD, an ancient Roman author, natural philosopher and naval
and military commander of some importance who wrote Naturalis Historia, tells
us that the Greeks and Romans crowned themselves with peppermint at their
feasts and adorned their tables with its sprays, and that their cooks flavoured
both their sauces and their wines with its essence.
The plant is found throughout Europe, in moist situations, along streambanks
and in wastelands.
3. Production levels
South Africa
Under irrigation and good management, peppermint will yield 20 to 25 tons
of plant material per hectare per year, at an oil recovery rate of 0,3 % or 60
to 75 kg essential oil per ha. Dryland production will generally be less, but it
will depend entirely on the quantity of rainfall and its frequency throughout the
season.
Internationally
World production is more than 4 000 metric tons per year, with the USA accounting for 80 % of this and, in addition, being an importer and re-exporter. The USA
mint produces an average 25 tons of herbage and 78,3 kg oil per ha at a 0,3 %
oil recovery rate.
Production of M. x piperita also takes place in Canada, Europe and Britain, Australia, Tasmania and New Zealand. The Asian continent also produces mint oil
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with India and China as the largest of these producers. The Japanese, cultivate
M. arvensis, var. piperascens. The Chinese cultivate M. arvensis, var. glabrata,
both have a higher menthol content than M. x piperita, but with lower overall quality. The increase in worldwide demand is currently at about 5 % a year, predominantly as a result of Asian market expansion.
4. Major production areas in South Africa
Peppermint can be grown in most parts of South Africa where rainfall of higher
than 1 000 mm per annum occurs with long periods of sunlight and cool night
temperatures. The latter are needed for the correct balance of high-quality oil
production and it limits the constituent menthofuran, which is undesirable in the
oil.
There are indigenous mint species growing in South Africa in the temperate
zones and these are indicators of where the crop can be grown successfully. The
best areas are the escarpment of
Mpumalanga, Gauteng, Eastern
Free State, higher altitudes of
KwaZulu-Natal, and areas in the
Eastern and Western Cape.
5. Description of the
plant
Mentha x piperita L. is a sterile,
perennial herb originating from a
hybridisation between watermint
(Mentha aquatica) and spearmint
(Mentha spicata), and therefore
must be propagated vegetatively. The entire plant has a very
characteristic sharp, mint odour,
because of the presence of the
volatile oil.
Peppermint (Mentha x piperita)
3
Mint leaves. From left to right peppermint, Eau de Cologne mint (M. citrata), Japanese
mint (M. arvensis var. piperascens, also known as var. japonica), horsemint or silver
mint (M. longifolia), Moroccan green mint (M. spicata), pineapple mint (M. suaveolens)
and Carinthian mint (M. carinthiaca = M. arvensis x M. suaveolens)
(Source: Gernot Kazer’s Spice Pages)
Stem
Peppermint is a summer-growing perennial with upright, usually purplish, smooth
stems growing to 1 m in height.
Leaves
The lance-shaped leaf margins are finely toothed, their surfaces smooth, both
above and beneath, or very slightly hairy (hardly visible), on the principal veins
and midrib on the underside.
Flowers
The whorled clusters of little reddish-violet flowers are in the axils of the upper
leaves, forming loose, interrupted spikes, and rarely bear seeds.
Essential part
The whole plant is cut at flowering stage for steam distillation. The oil is found on
the undersides of the leaves.
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6. Species and cultivars
Two main selections are currently used in commercial essential oil production
throughout the industry.
66 Black Mitcham is the original cross. It is highly valued but susceptible to a
soil-borne fungal disease, Verticillium wilt.
66 Todd Mitcham is a more wilt-tolerant selection which currently forms the bulk
of the world's production.
Japan cultivates M. arvensis, var. piperascens which has a very high menthol
percentage, but is inferior in quality to M. x piperita. The Chinese cultivate mostly
M. arvensis, var. glabrata.
7. Climatic requirements
Temperature
Peppermint is grown in cool to temperate regions. It needs long day lengths with
warm to hot conditions and cool nights for the right balance of oil compounds to
be produced during the growing phase.
Less desirable compounds, particularly menthofuran, form when the conditions
are too warm, especially at night.
Rainfall
Peppermint needs adequate rainfall on a regular basis in excess of 1 000 mm
per season if planted on dryland.
8. Soil requirements
Peppermint will grow well in most soil types, including heavy, moist soils if drainage is sufficient. On lands that are under water in winter it will not perform vigorously and plants may even die off. The best soils are deep, well-drained, rich
in humus, with good moisture retention. Soil samples are taken for analysis to
determine base fertility levels before mint is planted. The soil pH should be kept
between 5,5 and 7,0.
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Part II: Cultivation practices
1. Propagation
All commercial mint varieties are sterile hybrids
and must therefore be propagated vegetatively.
Propagat­ion is usually done by using the under­
ground stolons (runners or rootstock) from a nursery site. Dormant stolons are ploughed up.
The stolons cannot be stored for more than a few
days because they deteriorate rapidly owing to
heat or dehydration. Stolons can be planted by
hand or mechanically. Stolons should not have
too much top growth. About 1 ha of mother material can supply a cropping area of 7 to 10 ha.
2. Soil preparation
66 Have the soil analysed at a laboratory that will be able to check for mineral
deficiencies and excesses, organic status and carbon ratios.
66 A soil analysis will guide the producer in correcting the nutrient status of the
soil in order to provide the crop with optimum growing conditions such as a
balanced mineral status and correct pH.
66 Soil fertility levels have to be within acceptable ranges before starting a soilbuilding programme.
66 Correct the soil pH according to analysis and soil type.
66 Fertiliser use has to be planned according to whether the crop will be grown
inorganically or organically.
66 Soil preparation has to be done according to good cultivation practices.
66 Apply suitable soil preparation practices according to the farming operation.
rip, plough, disc, harrow, contour, etc.)
66 If mechanical harvesting and weed control is envisaged, prepare row widths
adapted to the machinery to be used.
6
Producers who treat their soil correctly will have the benefit of producing crops of
high value with less input in terms of weed, pest and disease control.
To build soil organic matter, the production or addition of organic
matter must exceed the decomposition
of organic matter
3. Planting
Planting density/spacing
Young shoots are planted 40 to 90 cm between rows and 15 to 45 cm within
rows lightly covered with soil. This practice will give a total of 55 000 to 75 000
plants per ha and will cover the soil quickly. A plantation lasts about 3 to 5 years,
depending on cultivation, soil and climatic factors. The best yields are obtained
from the second year.
Planting date
The plants are propagated in spring.
Design
The young shoots are transplanted into new soil, in shallow furrows. Another
way of planting is to spread the stolons over the land, using a modified manure
spreader and then discing it in lightly.
3. Fertilisation
The soil should have at least 120 kg phosphorus and 500 kg potassium available per ha. If the soil sample indicates levels lower than what is recommended,
fertiliser should be applied before planting.
Peppermint has to be fertilised properly to achieve a good crop. Nitrogen fertilisation is essential for foliage stimulation and improving the flavour and quality
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of oil. Fertiliser rates are generally high in order to allow good vegetal growth and
development of the maximum number of leaves. Frequent nitrogen applications
are required throughout the growing season to maintain soil fertility.
When manure or organic compost is used, it should be analysed for its properties to ensure correct application rates. The quality of the manure or compost
has a great effect on the characteristics of the oil. In trials in the USA application
of nitrogen at 200 kg/ha and organic mulch enhanced essential oil yield with improved water-use efficiency. Potassium application was found particularly useful
against a form of chlorosis or ‘rust’ (Puccinia menthoe) (Mitchell, 1998).
5. Irrigation
Peppermint requires frequent and adequate irrigation, which is used to supplement rainfall. When the plants are fully developed they are watered at least three
times a week. It is important to keep the soil constantly moist, although well
drained. The crop has high water demands in summer. Care has to be taken
to prevent a waterlogged soil, especially in winter, as this will influence growth.
Peppermint can be grown under flood and sprinkler irrigation. Pivots and booms
are the most labour-saving irrigation systems.
6. Weed control
Weed control programmes should be maintained strictly as weeds compete with
mint for available nutrients, thereby reducing yields. Care should be taken when
harvesting to avoid inclusion of weeds, which could result in volatile compounds
being extracted and reducing the oil quality. Certain weed species are more harmful and can reduce the marketability of the oil.
Amaranthus spp. (pigweed) and Datura spp. (thorn-apple) can reduce oil quality
severely. Hand removal of weeds may be necessary. Always remove the weeds
in time before they form seed.
Annual grasses can be a problem and have to be removed before they grow too
tall. Perennial weeds are sometimes a bigger problem, especially the Cyperus
spp. (nut sedges). It is more difficult to control these when the crop is established
because the chemicals to be used will affect essential oil quality.
8
Use the publication* A guide to the use of herbicides – 2004, compiled by Hermien
Grobler, J.B. Vermeulen & Kathy van Zyl
7. Pest control
Pests on peppermint include cutworms, loopers, mites, weevils, aphids, grasshoppers and soil nematodes. Most pests are troublesome on older mint fields,
especially nematodes. Using rootstocks from old lands for planting new lands
can introduce pest problems into the new lands.
For prospective producers of herbal and essential oil crops, the following pest
control guidelines are recommended:
Pest control guidelines
66 Natural pest control measures should be used as first choice.
66 Follow a pest management programme.
66 Regular scouting of the crop is needed.
66 Early detection and management of pest problems can prevent major problems.
66 Correct identification of pests and natural beneficial predators is essential.
66 Introduce and use biological control measures, natural predators, parasites,
nematodes, fungi, bacteria and beneficial microorganisms. Avoid using
chemicals that kill such organisms.
66 Other organic methods such as reflective mulches, insecticidal soaps, plant
extracts, traps and handpicking of pests, water sprays and vacuum, can be
used.
66 Use controls that target specific taxonomic groups, eating habits, or life
stages: insecticidal soaps, horticultural oils, pheromones, and growth-regulating natural substances such as neem oil.
66 The knowledge of certain herbs that repel or attract insects can be used in
companion planting for pest control.
*Obtainable from the Resource Centre, Directorate Communication Services,
Private Bag X144, Pretoria, 0001. Tel: 012 319 7141/7085. Fax: 012 319 7260
9
66 If organic practices are to be applied, make sure that products are certified
for use.
Extension officers from the Department of Agriculture and researchers from agricultural institutes should be contacted for further information on the identification
of insects and for recommended controls.
Use the publication* A guide for the control of plant pests – 2002, compiled by
Annette Nel, Mareli Krause, Neervana Ramautar & Kathy van Zyl.
8. Disease control
Peppermint is susceptible to several diseases of which rust, Verticillum wilt, leaf
spot diseases and anthracnose are important.  
Verticillium wilt is a fungus which is soil-borne and can survive in the soil indefinitely once spores build up in the soil. Infection occurs through natural openings
and wounds on roots. Crop rotation is only effective if it has been followed from
the beginning, before the pathogen is well established. It is good to rotate, using
a nonsusceptible crop every 3 to 4 years. Onions, maize and soya-beans are
good crops to rotate with mint to reduce the likelihood of buildup of verticillate
propagules in the soil. Todd’s Mitcham peppermint is less susceptible than Black
Mitcham peppermint.
Mint rust is considered a severe problem. The symptoms include light-yellow,
blister-like lesions on young shoots in the spring, and brownish-red spots surrounded by a yellow halo on the leaves later in the season. Affected leaves fall
off and defoliation can be severe. It is important to plough the mint beds to bury
overwintering spores. Elimination of volunteer mint plants will also reduce the
available rust inoculum.
Root lesion nematode (Pratylenchus penetrans) and other plant parasitic nematodes such as Trichodorus are frequently found on peppermint and nematodes
are soil-inhabiting pests that feed on the roots and stunt plant growth. Nematodes
have a synergistic relationship with Verticillium wilt in that they will increase the
number of wounds through which the Verticillium can infect the plants, there by
causing the plant to express more severe wilt symptoms.
*Obtainable from the Resource Centre, Directorate Communication Services,
Private Bag X144, Pretoria, 0001. Tel: 012 319 7141/7085. Fax: 012 319 7260
10
Use the publication* A guide for the control of
plant diseases – 2003, compiled by Annette
Nel, Mareli Krause, Neervana Ramautar &
Kathy van Zyl.
9.Other cultivation practices
Mint is sometimes cultivated as a fresh herb
or processed in dried form for tea and culinary
use.
10.Harvesting
A mature plant of peppermint
(Mentha piperita)
Maturity time and methods
Timing of harvest is critical to the quality of the oil.
Preharvest sampling can be done to ensure that
harvesting occurs when oil quality is best. In this sampling changes in oil composition from early January onwards are examined. Optimum oil yield and quality
is usually obtained when 10 % of the crop is in the flowering stage. Harvest­ing
should be carried out on a dry, sunny day, in the late morning, when all traces
of dew have disappeared. The crop is cut, using conventional hay mowers. It is
very important to make a clean cut without splintering the stems or shattering of
the leaves as this will result in lower oil yields and inhibit regrowth of the plants.
The cut mint is left in the field to wilt, after which it is chopped up with a forage
harvester into a mobile distillation pot or trailer to be transported to the stationary
distil­lation facility. Lower moisture content ensures economic oil extraction. Even
under the best condi­tions of wilting, there is a certain loss of essential oil from
lying in windrows or heaps for any length of time. Fermentation can occur if not
checked, reducing the quality and quantity of the oil. Some producers prefer to
distil the crop fresh as soon as cut.
If the crop is well irrigated and matured in time, a second crop can be obtained
in the same year. Unlike other essential oil plants, oil yield of peppermint will decrease rapidly if the plant is subjected to either physiological or pathological stress.
*Obtainable from the Resource Centre, Directorate Communication Services,
Private Bag X144, Pretoria, 0001. Tel: 012 319 7141/7085. Fax: 012 319 7260
11
Part III: Post-harvest handling
1. Sorting and distillation
The crop is steam distilled and the steam/oil vapour is condensed and separated.
Condensing and separation equipment should be manufactured from stainless
steel and a general processing hygiene followed to ensure no contaminants
are present. The time for oil extraction varies, depending on the type of steam
source, the herb weight, and the moisture content.
2.Grading
The main chemical constituent of peppermint oil is menthol, however, it also contains menthyl acetate and isovalerate, menthone, cineol, pinene, limonene and
other constituents. The quality of the oil is determined by the correct combination
of chemical constituents, especially menthol and menthone and the absence of
menthofuran. Once the oil is separated, the product is relatively stable for many
months, provided it is stored out of direct sunlight and away from heat.
Japanese oil has the highest percentage of menthol, 85 %, English oil contains
60 to 70 % menthol, and the American oil 50 %. The odour and taste is a good
indication of the quality of the oil, and by this means it is quite possible to dis­
tinguish between English, American and Japanese oils.
3.Packaging
Epoxy-lined, fluorinated plastic and galvanised drums are used for bulk storage
and transportation.
4.Storage
Peppermint essential oil should be stored in a cool, dry area until it is used. Once
opened, refrigeration and tightly closing the cap will prolong its shelf-life.
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5.Marketing
Essential oil market
The market for essential oils in South Africa is divided into local buyers and
international buyers. The local buyers include marketing agents and companies
from chemical and pharmaceutical, as well as food and flavouring industries.
The international buyers are divided into flavour and fragrance houses, cosmetics and personal health care, aromatherapy and food manufacturers who buy in
large quantities.
The major market in the world for essential oils is the United States, followed by
Japan and Europe. However, production continues to be concentrated in Eur­
ope, with seven of the world’s largest essential oil processing firms. In the United
States, the major users of essential oils are the soft drink companies. Japan accounts for 10 % of the world demand. The Canadian market is dominated by the
United States perfume and flavouring industry.
The floral water also known as hydrolat and the oil are bought by agents to supply cosmetic and aromatherapy companies.
The sale price
Price is largely regulated by the world supply and demand. Peppermint is presently being produced in countries with low labour costs such as China and India.
This can make it difficult for a South African farmer to compete, unless there is
a fair degree of value-adding applied. Organically grown mint oil is always in
demand and will fetch better prices.
Part IV: Production schedules
As farming enterprises are so diverse, a very basic schedule is proposed. Producers have to adapt the schedule to their own needs.
When scheduling production, the important factor to bear in mind is to
have sufficient knowledge of the crop that you are farming with
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Disking
Prepare seedbed
 
 
 
 
 
 
 
 
 
 
Jun
Harvest
 
 
 
 
 
 
May
 
 
 
 
 
 
 
Apr
Irrigate
 
Pest control
 
 
 
 
 
Mrt
 
 
Weed control
 
 
 
 
Feb
Disease control
 
Plant and transplant
Planting, cultivation and harvesting
 
Jan
Rip and plough
Field preparation
Activity
General crop schedule – peppermint
 
 
 
 
 
 
 
 
 
Jul
 
 
 
 
 
 
Aug
 
 
 
 
 
 
Sep
 
 
 
 
 
 
Oct
 
 
 
 
 
 
Nov
 
 
 
 
 
 
Dec
Part V: Utilisation
Main properties of peppermint are antiseptic, antispasmodic, carminative, cephalic, stimulat­ive and stomachic.
1.Industrial
Peppermint essential oil is mainly used as flavouring in toothpaste, ice cream,
confectionery, soft drinks, tobacco, chewing gum, and other varieties of foods. It
can also be found in shampoos, soaps, balms and liniments. The oil has a cooling effect for fevers.
Peppermint tea and tea blends are becoming more popular as a natural foodstuff. Peppermint tea is used for relief of palpitations of the heart and nausea.
2. Cosmetic
Constituent of certain perfumes are used for treatment of acne and dermatitis.
3. Medicinal and therapeutic
The therapeutic peppermint value lies in its ability to relieve flatulence, bloating and colic, inhibit the growth of certain bacteria, and can assist in smoothing
and relaxing muscles when inhaled or applied to the skin. It increases sweating,
stimulates secretion of bile, assists in curing ulcers. Peppermint eases nervous
headaches and is used for aid in cases of cholera and diarrhoea.
Peppermint is used to disguise the taste of unpalatable drugs, as it imparts its
aromatic characteristics to whatever prescription it enters into. In aromatherapy
the essential oil is used to stimulate hot and cold nerve endings and increase
blood flow.
4.Other
Peppermint is a deterrent to pests such as mice, ants and other insects. Peppermint and spearmint oils are both effective in reducing nematodes in the soil.
Recent concerns over the damage to the environment done by nematicides,
15
especially methyl bromide which also damages the ozone layer, have led to research for safer methods of protecting crops from nematodes in the soil.
5. Safety data
Nontoxic, nonirritant. Sensitisation could occur because of the menthol concentration. Use in well-diluted form. Because of its stimulant action, it should not be
used for prolonged periods of time.
References*
Bourweig, D. & Pohl, R. 1973. Flavonoids from Mentha longifolia. Planta Medica, 24: 304–314.
Chaumont, J.P. & Senet, J.M. 1978. Antagonistic properties of higher plants against fungal parasites of man from food contaminants: screening of 200 fungi. Planta Medica, 12: 186–196.
Diaz, R., Quevedo-Sarmiento, J., Ramos-Cormenzana, A., Cabo, P. and Cabo, J. 1988. Phytochemical and antibacterial screening of some species of Spanish Lamiaceae. Fitoterapia,
59(4): 330–333.
Du Preez, R. 2005. Herbs for the garden. Nelspruit, South Africa: ARC-Institute for Tropical and
Subtropical Crops.
Gotshall, R.Y., Lucas, E.H., Lickfeldt, A. & Roberts, J.M. 1949. The occurrence of antibacterial
substances active against Mycobacterium tuberculosis in seed plants. Journal of Clinical
Investigation, 28: 920–923.
Hegnauer, R. 1953. The content of essential oil and carvone in various species of mint. Ber.
Schweiz. Bot. Ges. 63: 90–102.
Katzer, G. Modification date: 28 July 2004. Peppermint (Mentha piperita L.). Online: http://www.
uni-graz.at/~katzer/engl/Ment_pip.html. Accessed 04 September 2008.
Ikram, M. & Haq, I. 1980. Screening of medicinal plants for antimicrobial activity. Part 1. Fito­
terapia, 51: 231–235.
Jawad, A.M., Jaffer, H.J., Al-Naib, A., Saber, H. & Razzak, A.A.W. 1988. Antimicrobial activity of
some Iraqi plants. Fitoterapia, 59(2): 130–133.
Lamaison, J.L., Petitjean-Freytet, C., Duband, F. & Carnat, A.P. 1991. Rosmarinic acid content
and antioxidant activity of French Lamiaceae. Fitoterapia.
Mimica-Dukic, N., Bozin, B., Sokovic, M., Mihailovic, B. & Matavulj, M. 2003. Antimicrobial and
antioxidant activities of three Mentha species essential oils. Planta Medica, 69: 413–419.
Mimica-Dukic, N., Jacovljevic, V., Mira, P., Gasic, O. & Szabo, A. 1996. Pharmacological studies on Mentha longifolia phenolic extracts. International Journal of Pharmacognosy, 34(5):
359–364.
Mitchell, a. 1998. Fertilizer guide: Peppermint and spearmint. Oregon State University, Corvallis.
Watt, J. M. & Breyer-Brandwijk, M. M. 1962. 2nd Edition. The Medicinal and Poisonous Plants
of Southern and Eastern Africa. London: E & S Livingstone Ltd.
*Further information on references could be obtained from members of SAEOPA and
KARWYL Consultancy.
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